(a) Field of the Invention
The present invention relates to a remover composition for removing resists during a manufacturing process of semiconductor devices such as integrated circuits (IC), large scale integrated circuits (LSI) and very large scale integrated circuits (VLSI).
(b) Description of the Related Art
Generally, manufacturing processes of semiconductor devices employ dozens of lithography processes that comprise forming a resist pattern on a conductive layer formed on a semiconductor substrate, and then etching a part of the conductive layer that is not covered by the pattern to remove it, thereby forming a conductive layer pattern using the pattern as a mask. The resist pattern used as a mask must be removed from the conductive layer with resist remover during the stripping process after the conductive layer pattern forming process. However, since in recent very large scale integrated circuit semiconductor manufacturing, a dry etching process for forming conductive layer patterns has been conducted, it has become difficult to remove resists in a subsequent stripping process.
In a dry etching process which replaces a wet etching process using liquid phase acids, the etching process is conducted using a gas-phase/solid-phase reaction between plasma etching gases and layers such as the conductive layer. Dry etching forms the main stream of recent etching processes, because it is easy to control and can obtain a sharp pattern. However, since during a dry etching process, ions and radicals of plasma etching gases cause complex chemical reactions with the resist film on its surface and rapidly cure it, it becomes difficult to remove the resist. Particularly, in the case of dry etching of a conductive layer such as tungsten and titanium nitride, the generated side-wall resists that have been cured and modified are difficult to remove even if various chemicals are used.
A recently suggested resist remover composition comprising hydroxylamine and aminoethoxyethanol has been widely used because of its properties of effectively removing most cured resist films. However, said remover composition causes serious corrosion of copper wiring metal layers that are applied in semiconductor manufacturing lines of 1 giga DRAM or more, instead of aluminum wiring. Thus, there is a need for the development of a novel resist remover that can compensate for this problem.
Meanwhile, a recently suggested resist remover composition comprising alkanol amine and diethyleneglycol monoalkyl ether has been widely used because it has little odor and toxicity and exhibits effective removing performance for most resist films. However, it has also been found that said remover composition cannot sufficiently remove resist film exposed to plasma etching gases or ion beams in a dry etching process or an ion implantation process. Thus, there has been a need for the development of a novel resist remover that can remove resist film modified by the dry etching and ion implantation processes.
As stated above, it is difficult to remove resist film that has undergone the ion implantation process using resist remover. Particularly, it is more difficult to remove resist film that has undergone the ion implantation process with high radiation dose for forming the source/drain area in the very large scale integrated circuit manufacturing process. During the ion implantation process, the surface of the resist film is cured mainly due to reaction heat from the high-energy ion beams and the high radiation dose. In addition, popping of the resist occurs which generates resist residues. Commonly, a semiconductor wafer that is ashing-treated is heated to a high temperature of 200° C. or more. At this time, solvent remaining inside the resist should be evaporated and exhausted, which is not possible because a cured layer exists on the surface of the resist after the ion implantation process with a high radiation dose.
Accordingly, as ashing proceeds, internal pressure of the resist film increases and the surface of the resist film is ruptured by solvent remaining inside, which is referred to as popping. The surface cured layer dispersed by such popping becomes residue, and thus it is difficult to remove. In addition, since the cured layer on the surface of the resist forms by heat, impurity ions, or dopants, are substituted in the structure of resist molecules to cause a cross-linking reaction, and the reacted area is oxidized by O2 plasma. Thus the oxidized resist changes into residues and particles to become contaminants, which lower the production yield of very large scale integrated circuit manfacture.
Many dry and wet etching processes for effectively removing the resist cured layer have been suggested, one of which is a two step ashing method comprising conducting common ashing and following with a second ashing process as described in Fujimura, Japanese Spring Application Physical Society Announcement, 1P-13, p574, 1989. However, these dry etching processes are complicated, they require a lot of equipment and they lower production yield.
In addition, a resist remover composition comprising an organic amine compound and various organic solvents has been suggested as a resist remover used in a conventional wet stripping process. Specifically, a resist remover composition containing monoethanolamine (MEA) as the organic amine compound is widely used.
As examples, a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), 2-(2-aminoethoxy)ethanol (AEE), etc., and b) polar solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), carbitol acetate, methoxyacetoxypropane, etc. (U.S. Pat. No. 4,617,251); a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), monopropanolamine, methylamylethanol, etc., and b) amide solvents such as N-methylacetamide (Mac), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), N,N-dimethylpropionamide, N,N-diethylbutylamide, N-methyl-N-ethylpropionamide, etc. (U.S. Pat. No. 4,770,713); a two-component system resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), and b) non-protonic polar solvents such as 1,3-dimethyl-2-imidazolidinone (DMI), 1,3-dimethyl-tetrahydropyrimidinon, etc. (German Laid-Open Patent Application No. 3,828,513); a resist stripper composition comprising a) ethylene oxide-introduced alkylene polyamines of alkanol amines such as monoethanolamine (MEA), diethanol amine (DEA), triethanolamine (TEA), etc., and ethylenediamine, b) sulfone compounds such as sulforane, etc., and c) glycol monoalkyl ethers such as diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, etc., in a specific ratio (Japanese Laid-open Patent Publication No. Sho 62-49355); a resist stripper composition comprising a) water soluble amines such as monoethanol amine (MEA), diethanolamine (DEA), etc., and b) 1,3-dimethyl-2-imidazolidinone (Japanese Laid-open Patent Publication No. Sho 63-208043); a positive resist stripper composition comprising a) amines such as monoethanolamirie (MEA), ethylenediamine, piperidine, benzyl amine, etc., b) polar solvents such as DMAc, NMP, DMSO, etc., and c) a surfactant (Japanese Laid-open Patent Publication No. Sho 63-231343); a positive resist stripper composition comprising a) nitrogen-containing organic hydroxy compounds such as monoethanolamine (MEA), b) one or more solvents selected from diethylene glycol monoethyl ether, diethyleneglycol dialkyl ether, γ-butyrolactone and 1,3-dimethyl-2-imidazolinone, and c) DMSO in a specific ratio (Japanese Laid-open Patent Publication No. Sho 64-42653); a positive resist stripper composition comprising a) organic amine compounds such as monoethanolamine (MEA), etc., b) a non-protonic polar solvent such as diethylene glycol monoalkyl ether, DMAc, NMP, DMSO, etc., and c) a phosphate ester surfactant (Japanese Laid-open Patent Publication No. Hei 4-124668); a resist stripper composition comprising a) 1,3-dimethyl-2-imidazolidinone (DMI), b) dimethylsulfoxide (DMSO), and c) organic amine compounds such as monoethanolamine (MEA), etc. (Japanese Laid-open Patent Publication No. Hei 4-350660); and a resist stripper composition comprising a) monoethanolamine (MEA), b) DMSO, c) catechol (Japanese Laid-open Patent Publication No. Hei 5-281753) have been suggested and these resist stripper compositions show relatively good properties in terms of their stabilities, processabilities and resist removing performances.
However, one of the recent tendencies of semiconductor device manufacturing processes is treating various substrates including silicon wafers at a high temperature of 110 to 140° C., and thus resists are often baked at high temperatures. However, said resist strippers do not have sufficient capabilities for removing resists that are baked at high temperatures. As compositions for removing the hard baked resists, resist remover compositions containing water and/or hydroxylamine have been suggested. As examples, a resist stripper composition comprising a) hydroxylamines, b) alkanol amines, and c) water (Japanese Laid-open Patent Publication No. Hei 4-289866; a resist stripper composition comprising a) hydroxylamines, b) alkanol amines, c) water and d) anti-corrosives (Japanese Laid-open Patent Publication No. Hei 6-266119); a resist stripper composition comprising a) polar solvents such as GBL, DMF, DMAC, NMP, etc., b) aminoalcohols such as 2-methylaminoethanol, and c) water (Japanese Laid-open Patent Publication No. Hei 7-69618); a stripper composition comprising a) aminoalcohols such as monoethanolamine (MEA), b) water, and c) butyidiglycol (Japanese Laid-open Patent Publication No. Hei 8-123043); a resist stripper composition comprising a) alkanolamines, alkoxyamines, b) glycol monoalkyl ether, c) sugar alcohols, d) quaternary ammonium hydroxide, and e) water (Japanese Laid-open Patent Publication No. Hei 8-262746); a stripper composition comprising a) one or more alkanolamines of monoethanolamine (MEA) or AEE, b) hydroxylamine, c) diethyleneglycol monoalkyl ether, d) sugars (sorbitol), and e) water (Japanese Laid-open Patent Publication No. Hei 9-152721); a resist stripper composition comprising a) hydroxylamines, b) water, c) amines having an acid dissociation constant (pKa) of 7.5 to 13, d) water soluble organic solvent, and e) an anticorrosive (Japanese Laid-open Patent Publication No. Hei 9-96911) have been suggested.
However, said resist stripper compositions are not satisfactory in terms of either their removing performances for resist films cured by dry etching, ashing and ion implantation processes and those modified by metallic side-products etched from lower metal film materials during said processes, or anti-corrosive performances of lower metal wiring during the resist removal process.